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Centro de Investigaciones Biológicas del Noroeste (CIBNOR) 2011

Desertificación de cuencas agrícolas en Baja California Sur

Mercado Mancera, Gustavo

Titre : Desertificación de cuencas agrícolas en Baja California Sur

Auteur : Mercado Mancera, Gustavo

Etablissement de soutenance : Centro de Investigaciones Biológicas del Noroeste (CIBNOR)

Grade : Doctorado en Ciencias en el Uso, Manejo y Preservación de los Recursos Naturales 2011

The desertification is degradation process of earth in arid and semiarid areas and sub humid droughts, due for many factors, natural of anthropogenic origin. These last ones have been through inadequate handling of the ground, to the deforestation, overgrazing, and inadequate use of water and to the process of change of use of the ground. The aim of the work was to study the edaphic-hydro-climatic variables that affect the environmental deterioration and its impact in the socio-economic conditions, of the producers of the agricultural watersheds of La Paz and Comondu, B.C.S. To adapt and calibrate the hydroclimatic aridity model of De Martonne, modifying it to make it adequate for the study of the water balance in arid and semi-arid areas. A numerical analysis of the Aridity Index [A = 12pp=(t + 10)] was carried out in order to detect its sensitivity to rainfall and temperature gradients, where A is the Aridity Index of De Martonne, pp is the monthly rainfall, and t is the average monthly temperature. The modified equation was assayed and correlated using data of 1978 to 2008 from weather stations located in the watersheds of La Paz and Comondú, B.C.S. 142 samples were taken from soli in different conditions (presumably affected soil vs inalterable natural soil vs agricultural soil in apparent stability). The soil like pH, electrical conductivity, majors and minors nutrients, sodium, organic matter, texture, salinity were determined, among others. 3 water samples from 24 different wells were taken between October 2007 and to October 2008, determining the pH, electrical conductivity, sulfates, chlorides, salinity, alkalinity, dissolved oxygen and hardness. The results indicated that the floors are clear sandy, clear color, pH between 7.8 and 7.5. Poor in matter organic, they tend the salinity with values that oscillate of 45 to 8,070 μScm-1. The others chemicals elements are low except the sodium. The average annual temperature of 24.3 ºC, 170.2 mm of rain and 1,898.4 mm of ETP. The water salinity is low-medium (1,500 – 4,000 μS cm-1), with an increment in the quantity of total dissolved solid (1,100 to 1,900 mg L-1), same as in chlorides and sulfates (400 to 1,500 mg L-1 and 50 to 100 mg L-1, respectively). The pH tends to diminish (7.8 to 7.4) as well as dissolved oxygen (7.2 to 4.8 mg L-1). La Paz presented a monthly average index of 4.96, and Comondú recorded a value of 5.16. The equation of the fitted model was IDHA = 0.176012 + 0.101391-pp, where IDHA is the hydro-environmental availability index and pp is the monthly rainfall, with R2 = 94.8% and r = 0.97 indicating a close relationship between pp and IDHA. The modification applied to the De Martonne Index was numerically functional, with a high potential of application to hydrological studies of arid and semi-arid areas. Human interactions with land and water, cause deterioration in the environmental conditions and favor the process of desertification in the two studied watersheds ; the salinity of water and soil is factors favors that it in watersheds of Comondu, whereas the change of use of soil, the deforestation and saline intrusion, put in risk to the watersheds of La Paz. Therefore, the socioeconomic level of the producers catalogued like means, is falling before the loss of the productivity of the agricultural fields

Mots Clés : Suelo ; agua de riego ; clima ; índice hidro-ambiental ; desertificación


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Page publiée le 27 octobre 2017, mise à jour le 26 décembre 2019